Remove item from list if a string from another object contains substring

Question

I am trying to remove items from slices(list) whose substring is a part of pic(string) value from status2. I have tried various ways but there is always some issue such as sometimes it doesn't iterate over every item, sometimes it returns the exact same list.

slices = ['face_06_01.png', 'face_B45_06_01.png', 'face_gh_06_01.png', 'face_HJ_06_01.png']
status2 = [{'key': 1, 'pic': 'face_01_01.png', 'status': 2}, {'key': 2, 'pic': 'face__B45_02_01.png', 'status': 2}, {'key': 4, 'pic': 'face_gh_04_01.png', 'status': 2}]

for part in slices:
    pic_name = part[:-10]
    for status2_pic in status2:
        if pic_name in status2_pic['pic']:
            slices.remove(part)
            break

Output I get:

slices = ['face_B45_06_01.png', 'face_HJ_06_01.png']

Output I want according to the sample data:

slices = ['face_HJ_06_01.png']

This is where I am testing the code for now:

Does this answer your question? [How to remove items from a list while iterating?](https://stackoverflow.com/questions/1207406/how-to-remove-items-from-a-list-while-iterating) — Iguananaut, Jul 30 '21 at 07:47
I marked this as a duplicate, because from looking at your code I believe you're running into the common problem in Python of removing items from a list while iterating over it, which can cause exactly the kinds of problems you're describing. One quick workaround is to duplicate the list when iterating over it like `for part in slices[:]:` — Iguananaut, Jul 30 '21 at 07:48
Please see the example in the code. I have updated it. @CutePoison — ali baig, Jul 30 '21 at 07:58
Note that you have a double under-score in `key:2` `face__B45` — CutePoison, Jul 30 '21 at 08:06
Could you explain the output you want. How are you getting that ? @alibaig — Ram, Jul 30 '21 at 08:23
I am trying to remove items from slices(list) whose substring is a part of pic(string) value from status2. I have mentioned the output I want in the question. @Ram — ali baig, Jul 30 '21 at 09:11
I mean add an example in your question and explain us how you are getting that output you wanted. So ```f``` is a substring in all the items of ```slices``` and all values of ```pic```. Does that mean you have to remove everything from ```slices``` ? — Ram, Jul 30 '21 at 09:15
The list of Slices contains file names as I have provided the sample list in the question. The other variable is status2 which has a pic(string) in it. I want to match the start of pic(String) such as in the case of face_BHd_01_01.png; it would be face_BHD, in case of face_01_01.png; it would be face. Now I want to match face_BHD and face with each value of slices if this substring is a part of slices item values, then that item should be removed from the slices. — ali baig, Jul 30 '21 at 09:24
Ok. So for ```face_gh_06_01.png``` the slice is ```face_gh```; ```face_HJ_06_01.png``` the slice is ```face_HJ```. Am I right ? — Ram, Jul 30 '21 at 09:30

alparslan mimaroğlu · Accepted Answer · 2021-07-30T09:42:06.807

2

This should work. You don't have to remove the items one by one. List comprehensions are your friend :)

slices = [slice for slice in slices if slice[:-10] not in str(list(map(lambda x: x['pic'], status2)))]

edited Jul 30 '21 at 09:42

answered Jul 30 '21 at 07:49

alparslan mimaroğlu

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Did you run this ? What output did you get ? – Ram Jul 30 '21 at 07:50
No, but I am fairly confident it will run. Did it cause a problem in your end? – alparslan mimaroğlu Jul 30 '21 at 07:52
No. It wont't. Try running it and see for yourself. You will understand the problem. – Ram Jul 30 '21 at 07:53
status2 is not a list so it will cause an error. – Maisum Abbas Jul 30 '21 at 07:54
changed the comment to work with a list of dictionaries – alparslan mimaroğlu Jul 30 '21 at 08:07
It doesn't remove anything @alparslanmimaroğlu – ali baig Jul 30 '21 at 09:12
Yes it did not check for substrings. I edited the code again. Now it also checks for substrings – alparslan mimaroğlu Jul 30 '21 at 09:42

Ram · Answer 2 · 2021-07-30T09:56:52.987

2

You can try something like this using List Comprehension.

I am using .startswith() to specifically filter out results that start with the substring.
If you just want that substring to exists irrespective of position. Use in.

if s in i['pic']:

slices = ['face_06_01.png', 'face_B45_06_01.png', 'face_gh_06_01.png', 'face_HJ_06_01.png']
status2 = [{'key': 1, 'pic': 'face_01_01.png', 'status': 2}, {'key': 2, 'pic': 'face__B45_02_01.png', 'status': 2}, {'key': 4, 'pic': 'face_gh_04_01.png', 'status': 2}]

def check(s):
    for i in status2:
        if i['pic'].startswith(s):
            return True
    return False

slices = [x for x in slices if not check(x[:-9])]

print(slices)

['face_B45_06_01.png', 'face_HJ_06_01.png']

edited Jul 30 '21 at 09:56

answered Jul 30 '21 at 09:45

Ram

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`slices = ['face_HJ_06_01.png']` It should return this but thank you for the help. – ali baig Jul 30 '21 at 09:55
It's working fine. there's was a typo in face__B45 which should be face_B45 and then it would display the correct result – ali baig Jul 30 '21 at 09:57

Remove item from list if a string from another object contains substring

2 Answers2